620 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



steps which have been taken in the direction of improving the different 

 strains of Citrus trees in the groves of Cahfornia. Hitherto little or 

 no selection of buds has been practised. The buds are mostly procured 

 from successful growers of a given variety, without any regard to the 

 bearing capacity of the individual parent, and in some instances they 

 are even cut from nursery stock, when no selection based on crop 

 production is possible. This indiscriminate method of obtaining buds 

 for propagation may be partly due to the fact that the introduction of 

 commercially successful varieties of Citrus fruits into California is com- 

 paratively recent, and so far the demand for these trees has been greater 

 than the supply. It has been found, however, that there are desirable 

 qualities in individual trees which may be handed on, and the first 

 object of these investigations was to determine definitely the per- 

 formance of individual trees under uniform conditions for a period of 

 at least five years. Having ascertained that some trees habitually 

 yield larger crops of more valuable fruit than other trees of the same 

 variety under like conditions, and further that these desirable qualities 

 are transmissible to young stock propagated from such trees, it followsj 

 that the propagation of an improved type of the variety from selected 

 individual trees should be both possible and practicable. 



So far the trees have not been long enough under observation for it 

 to be safe to assume that the good and bad yielders are quite consistent 

 in their behaviour. A series of consecutive performance records is 

 necessary before selecting reliable stock, and methods of securing these 

 data and tabulating them for intelligent interpretation are described ic 

 this bulletin. The investigations are being carried on at present with 

 Washington Navel Oranges and Marsh Pomelos near Riverside, 

 California, and if desirable the work will be extended to other districts 

 of the Citrus belt and to deciduous and other fruits. — M . L. H. 



Club-root disease in the Cabbage family. By D. Houstor 



{Gard., March 4, 1911, p. 97). — This well-known and troublesomt 

 disease manifests itself first in the form of tiny swellings upon the 

 young roots of seedhngs which, as the plants grow, get bigger, unti 

 finally the greater part of the root system is converted into an enlarge( 

 mass of diseased tissue. In the last stage of the disease the root passe! 

 into a soft rot, and gets gradually incorporated with the surrounding 

 soil. The disease is due to a fungus which lives as a parasite withii 

 the tissues of the root. It has been found that this fungus thrive: 

 best in an acid soil. The remedj^ in such cases is heavy dressing!; 

 of quicklime at the rate of thirty-five bushels to the acre (about one pect' 

 to the rod). While this seems the only practical remedy, the following: 

 precautions are recommended : — ' 



(1) Examine the roots of the seedlings and burn those that shovj 

 signs of disease. 



(2) Avoid using manure likely to contain roots of clubbed plants 

 and do not carry soil attached to boots that have walked on or use tooli 

 that have worked in club-infested ground. 



